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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorrevor
    • CommentTimeNov 1st 2020
     
    As someone who is set on installing a battery for PV storage I cannot fathom out why these batteries are so expensive compared to those in cars. I recently read on a motoring site that a replacement 40kw battery for a Nissan leaf is £5k. 40 KW worth of solar battery would set me back in the region of £12K to £15K at least. A mini car from China Baojun 300 you can have for ca $9000 complete with 17kw battery. Can't think anything much to do with sales volume the cells are typically the same in EV and solar pv batteries.
    •  
      CommentAuthordjh
    • CommentTimeNov 1st 2020
     
    The £5k price you have seen is I believe a replacement price. i.e. You give them your old battery pack and they give you a new one to replace it. The article I found was dated 2014 so I don't know what the current price is. And the price may or may not be subsidised of course, since it's only for captive customers who own a Leaf.
  1.  
    for ref approx £5k ex will get you 3.5kW- 17.6kWh HV system, at trade
    •  
      CommentAuthorfostertom
    • CommentTimeNov 1st 2020
     
    The batteries in a Powerwall AFAIK are those very same post-vehicle batteries getting a second life in the kinder regime of a domestic installation.
    • CommentAuthorEd Davies
    • CommentTimeNov 1st 2020
     
    Posted By: fostertom: “The batteries in a Powerwall AFAIK are those very same post-vehicle batteries getting a second life in the kinder regime of a domestic installation.”

    This article corresponds with what I thought I'd heard elsewhere, that the cells in the Powerwall are a different chemistry from the Tesla vehicle batteries and so definitely not post-vehicle ones. Apart from anything else, I doubt there are that many Tesla vehicle batteries that have reached end of road life yet.

    https://electrek.co/2017/05/04/tesla-battery-researcher-chemistry-lifcycle/

    “Interestingly, Tesla currently uses nickel cobalt aluminum (NCA) battery cells for its vehicles. For its stationary energy storage products, like the Powerwall and Powerpack, the company uses nickel manganese cobalt oxide (NMC) cells, which typically have a longer cycle life, but less energy density.”
    • CommentAuthorEd Davies
    • CommentTimeNov 1st 2020
     
    Posted By: jamesingramfor ref approx £5k ex will get you 3.5kW- 17.6kWh HV system, at trade
    “HV”?
    • CommentAuthorEd Davies
    • CommentTimeNov 1st 2020
     
    Posted By: revor…a replacement 40kw battery…
    Obligatory kWh :devil:
  2.  
    HV = High voltage , PV (DC-DC) direct to battery (100-400v)
    rather than LV (48v) DC-AC-DC double inversion more common with retro fit battery systems
    •  
      CommentAuthordjh
    • CommentTimeNov 1st 2020 edited
     
    Any brand names, and what's the ratio of trade to retail prices?

    edit: And Tesla are just starting to use Li-ion phosphate batteries on cars produced in China, I believe.
  3.  
    thats for a SolaX triple power
    LGchem HV are more expensive
    Pylontech LV a bit cheaper.
    not sure what mark ups other people are charging ,
    theyre pretty expensive already. I work on the standard builders 15%ish for most stuff , but it all a bit variable, (quick nose around and its probably 20-25%)
    since the internet was invented the list and discount pricing seems very dated. I still find it funny the old school builder merchants think theyre doing you a favor giving you 60% discount whilst still charging twice what anyone can get things delivered to their door next day for 10am for
    • CommentAuthordereke
    • CommentTimeNov 2nd 2020
     
    I've just started looking into building a battery (to better take advantage of octopus agile).
    You can get LifePo4 cells from china (check alibaba) very cheap - around £750 for 10kWh (+shipping)
    Then you need a hybrid inverter, a reputable one (you want a good one from what I can tell) is around £1,500.
    I haven' figured out if there is much else needed, possibly a BMS if the inverter doesn't have one.
    But less than £3k for a 10kWh is quite good value I think!
    • CommentAuthorrevor
    • CommentTimeNov 2nd 2020
     
    For many reasons collected over many years I do not want my money to go to China.It is very difficult to find other sources but they are around. I am able to source a German designed and assembled battery made from cells manufactured in Korea. It is actually quite difficult to find out where battery components come from. In enquiring from one EV manufacturer where the batteries were made, as I was considering one of their models they would not divulge where the cells came from but would state where they were assembled.
    • CommentAuthordereke
    • CommentTimeNov 2nd 2020
     
    fair enough - where do you look for non china sourced batteries?
    • CommentAuthorrevor
    • CommentTimeNov 2nd 2020
     
    You ask the manufacturer. Some will tell you others won't. Asked recently a British manufacturer who gave me quite a bit of technical info but did not reply when I asked where the cells came from. The British distributor of the German battery told me it was all made in Germany but when I asked the actual manufacturer where the cells came from they told me. I do not believe one is told deliberate untruths it is more in the realms that they think they know but don't know that really, they don't know. I wanted non Chinese solar panels asked UK sales office which models came from Korea was told ordered they came made in China. Took a while to get them exchanged but they came good in the end. Often you have to be like a dog with a bone keep checking and cross checking until it all adds up. Been caught out too often. Needed solar cable checked spec on sellers website was suspicious checked the manufactures website it was different. Emailed them was told no one in UK sourced cable from them. Back to UK seller they checked up on their supplier of the cable, they had switched source and not told the seller. So spec on website was wrong. It is a minefield all down to lack of attention to detail just like the rest of the building industry.
    • CommentAuthorrevor
    • CommentTimeNov 4th 2020
     
    Came across this
    https://www.bing.com/videos/search?q=using+EV+battery+to+power+house&docid=608007712599048600&mid=E7AA33AA8741674D3DBAE7AA33AA8741674D3DBA&view=detail&FORM=VIRE
    Bit long winded but useful look see how Tesla car batteries are installed. Guy bought battery from Tesla write off and used it in an off grid situation replacing lead acid ones. Worth just skipping through for the interesting bits if you ever wondered what is under the floor of a Tesla EV.
    •  
      CommentAuthordjh
    • CommentTimeNov 4th 2020
     
    Are there any plug-an-play systems that also providing islanding in the event of a power cut? i.e. act as a UPS? We've had 3 brief power cuts in the past month and lots since we moved in. Given that we have a new underground connection, I find that somewhat annoying and would like to fix the problem.
    • CommentAuthorrevor
    • CommentTimeNov 4th 2020
     
    What I have come across so far apart from the expensive Tesla battery and gateway unit is a Delios inverter which has the switching built in to isolate from the grid and connect to the battery. There is a delay of about 30 secs before battery start powering. The inverter can also turn on a generator set as well. The only other one I have stumbled on is the Powervault 3 which in Jan 2021 will have an UPS facility. Think this one will integrate easily to an existing solar PV system. I too have outages sometimes just a couple of seconds so there is no advantage having UPS in this situation and there is no way I think one will get a step less system do to the requirement to disconnect from the grid. I also think that one needs to separate some of the circuits from the consumer unit into a second one so that the battery powers this second one, powering the essential low power consumption loads .
    • CommentAuthorborpin
    • CommentTimeNov 4th 2020 edited
     
    Posted By: djhAre there any plug-an-play systems that also providing islanding in the event of a power cut? i.e. act as a UPS? We've had 3 brief power cuts in the past month and lots since we moved in.
    Your issue will be that the power in the house should disconnect from the supply when there is a power cut so when they come to fix it, the line is not live (from your end). A UPS just supplies onward power i.e. everything goes through the UPS. Whatever you had would need to be on the supply side of your consumer unit.

    This was one of the issues when there was the large power outage a while back. The strike on the sub station caused the disconnection of something like half a MW of embedded generation.
    • CommentAuthorJecop
    • CommentTimeNov 4th 2020
     
    SMA Sunny Boy Storage (SBS) has an optional automatic transfer switch that will disconnect the home from the grid in case of grid failure. It allows the solar inverters as well as the battery inverter to keep providing energy during blackouts. Takes about 5s to switch.
    https://www.sma-sunny.com/en/backup-options-with-sunny-boy-storage/
    •  
      CommentAuthordjh
    • CommentTimeNov 5th 2020
     
    Posted By: revorI too have outages sometimes just a couple of seconds so there is no advantage having UPS in this situation

    That's exactly the situation I want to protect against. And that's what UPS do protect against, among other things.

    I suspect most of the failures we get are switching transients where the DNO automatically reroutes around some crappy piece of their overhead wire somewhere. But that's enough to reboot my PC, wipe the clocks on all the kitchen devices so they need to be reset, stop the PVR in the middle of recording and sometimes take down some of my pi and make them fail to reboot. So any interruption at all is very annoying.
    •  
      CommentAuthordjh
    • CommentTimeNov 5th 2020
     
    Posted By: borpinYour issue will be that the power in the house should disconnect from the supply when there is a power cut so when they come to fix it, the line is not live (from your end).

    Yes, clearly. I don't want to be powering the entire neighbourhood!
    • CommentAuthordereke
    • CommentTimeNov 5th 2020
     
    from what I can tell you want to get a hybrid inverter, it handles grid disconnections (as far as I am aware but I haven't completely confirmed this yet, you may need an additional piece of equipment) and can supply power immediately when the grid goes down

    Something like this - https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva
    •  
      CommentAuthordjh
    • CommentTimeNov 5th 2020
     
    Posted By: derekefrom what I can tell you want to get a hybrid inverter, it handles grid disconnections (as far as I am aware but I haven't completely confirmed this yet, you may need an additional piece of equipment) and can supply power immediately when the grid goes down

    Something like this https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

    Thanks, that looks like exactly the kind of thing. Apart from the cost I suppose the problem will be what happens if the power cut occurs whilst the kettle is on or we're cooking dinner, or in the middle of the night when the heating is on. I guess I would have to buy a bunch more smart control gear to immediately switch those off when there was a power cut.
    • CommentAuthorrevor
    • CommentTimeNov 5th 2020
     
    From what I can make out there are very few hybrid inverters that handles auto grid disconnects. The Tessla system as mentioned has the box called gateway that handles the switch over this is covered in one of the fully charged you tube videos. But this takes a few seconds despite its expense. I think if it was immediate they would have done it. The difference between a UPS and a battery I guess is that an UPS e.g.that powers the computer the UPS does not feed into the grid at 230 volts it powers the equipment it is protecting.

    https://www.youtube.com/watch?v=gP51JjnWvLo&list=PLzD0K2OhbVfEaxtwOfUmiDE17pf__Ialo&index=7&t=80s

    One of the popular hybrid inverters Solax and its accompanying battery does not switch over automatically it can be configured so that you have a manual switch which disconnects you from the grid and over to the battery. It seems the hybrid systems are geared up to help you manage usage and store your excess solar production and store cheap night energy but needs a feed from the grid. The Delios is the only one I have found so far that will switch over automatically but that is not to say there are others. I have the same issue as DJH get a power dip have to go round resetting clocks very frustrating on ovens that have cost £1000 which are in themselves programmable. It might be worth exploring the Powervault3 as in their brochure they use the term UPS. Available next January. The only way, certainly currently to avoid dips and disruption to supply, is go off grid.
  4.  
    UPS 'hats' are available for RPi
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